Add DualStarRocksWriter for dual-writing to two StarRocks clusters

[decli]

Add support for dual-writing to two StarRocks clusters for cross-room data disaster recovery.

• Add DualStarRocksWriter class to handle dual-writing to two StarRocks clusters.
• Implement Job and Task inner classes in DualStarRocksWriter to manage configuration and writing logic.
• Add configuration options for the second StarRocks cluster in plugin_job_template.json.
• Update plugin.json to include the new DualStarRocksWriter entry and description.

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